Key Takeaways
- A water meter that moves with every fixture off means a leak somewhere.
- A few drops of food coloring in the toilet tank reveal a silent toilet leak.
- Warm floors, musty smells and stained ceilings point to hidden leaks.
- Fix small leaks fast, because hidden water damage grows quietly.
Why Small Leaks Matter
According to the EPA's WaterSense program, household leaks can waste nearly 10,000 gallons of water a year, and a faucet dripping once a second wastes more than 3,000 gallons. The bigger cost is often hidden: water rotting a subfloor, staining a ceiling, or feeding mold inside a wall long before anyone notices.
Test 1: The Water Meter Test
- Turn off every faucet, appliance and irrigation zone, and make sure nobody uses water.
- Find your water meter and note the reading, or watch the small leak indicator dial.
- Wait 30 minutes to an hour without using any water.
- Check again. If the reading changed or the indicator moved, water is leaving the house somewhere.
If the meter moves, close the main shut-off inside the house and check again. If it stops, the leak is inside. If it keeps moving, the leak is in the service line between the meter and the house.
Test 2: The Toilet Dye Test
Toilets are the most common silent leak. Put a few drops of food coloring in the tank and wait 15 minutes without flushing. If color shows up in the bowl, the flapper is leaking. It's an inexpensive fix. See our toilet repair page.
Signs of a Hidden Leak
- A water bill that rises while your habits don't change
- Musty smells or mold in cabinets, closets or basements
- Stains, bubbling paint or soft drywall on ceilings and walls
- Warp, lift or soft spots in floors
- Warm spots on a floor, which can mean a hot water line leaking under a slab
- The sound of running water when everything is off
Where Leaks Usually Start
| Location | Common cause |
|---|---|
| Under sinks | Loose connections, failed supply lines, leaking traps |
| Toilets | Worn flapper, fill valve, wax ring |
| Water heater | Relief valve, drain valve, corroded tank |
| Washing machine | Rubber supply hoses that crack with age |
| Under the slab | Corroded or abraded supply lines |
| Behind showers | Failed valve or fittings in the wall |
Leaks You Can Fix Yourself (and Ones You Shouldn't)
Tightening a loose connection under a sink, replacing a toilet flapper, swapping rubber washer hoses for braided stainless ones, and fixing a dripping faucet are reasonable DIY jobs. Our leaky faucet guide walks through the last one.
Leaks inside walls, under slabs, at the water heater tank, or anywhere near gas or electrical lines are jobs for a licensed plumber. Finding the source precisely, before opening walls, is what our leak detection service does. Then plumbing repair fixes it.
If water is near outlets, appliances or the electrical panel, turn off power to that area at the breaker before you touch anything.
Repeated Leaks Mean Old Pipe
If pinhole leaks keep showing up in different places, the pipe walls are wearing out, and patching won't keep up. A plumbing inspection tells you whether it's time to repipe. We help homeowners across Rockville, North Bethesda and Gaithersburg find and fix leaks early.
